Figures from the Central Bank show that the percentage of mortgage holders who are behind on their repayments climbed to 5.7% by the end of 2010.
There was also an increase in the number of repossessions.
The Central Bank said 44,508 mortgage accounts were more than 90 days behind with repayments by 31 December last year.
This was up from 40,472 (5.1%) of all mortgages at the end of September.
Mortgage holders in arrears owe a total of €8.6bn, which is up from €7.8bn three months earlier.
Of the 44,508 mortgages in arrears, more than 31,000 are more than 180 days behind with repayments.
The Central Bank adds that another 35,205 mortgages have been classified as 'restructured' but performing.
This means people in difficulty with mortgages have made arrangements with their lender to make it easier for them to make repayments.
There were 106 properties repossessed during the final three months of last year, compared with 81 in the third quarter.
Mortgage lenders held 585 repossessed properties by the end of 2010, up from 521 at the start of the period. They managed to sell 42 properties during the three-month period.
There was a big increase in lenders applying to the courts to start proceedings over mortgages that were in arrears.
The 297 cases in the quarter represented an increase of more than 40% from the previous three months.
